Homeland Security Investigations (HSI) agents began raiding a warehouse at 1461 15th St. early Tuesday morning in what local police have characterized as a potential child pornography investigation.

Agents were spotted going in and out of the building at 7 a.m. The 2,750-square-foot building has two units and three rooms, and is designated for “industrial” use, according to Planning Department records.

Agents departed around 11:30 a.m.

“My understanding is that HSI is doing an investigation into child pornography,” San Francisco Police Department spokesman Sgt. Michael Andraychak said in an email.

The building was the 40-year home of Porter Auto Trim until that business closed in 2012. As long ago as 2010, however, city inspectors claimed that “residential units” were on the property. A startup is registered to this address as well; calls to it have not been returned.

Christi Azevedo lives one house down from the warehouse. She says she often saw people coming and going with luggage in tow.

“They just seemed like white kids in their 20s. You don’t see them around much,” she said. “They keep a low profile.”

She said she only spoke to residents of the warehouse once, to alert them about street sweeping. One of the inhabitants of the warehouse had a car, and she was trying to alert him about the parking control officer by knocking on the door. She recalled that the owner of the car did not like being bothered.

“Homeland Security Investigation (HSI) agents were implementing a law enforcement action in support of an ongoing criminal investigation at the location you provided,” said Immigration and Customs Enforcement (ICE) spokesman Paul Prince (HSI operates under the aegis of ICE). “No further information pertaining to this investigation is available at this time. Please feel free to check back for updates.”

A man who identified himself as a resident of the building — one of six purportedly living on-site — said he believed the raid was targeting a guest who had been visiting the site. This man was, reportedly, not present. The building resident said electronics belonging to the guest were carted off by federal agents.

This is a breaking story and will be updated as information comes to light.